Cystoid Macular Edema in Non-Syndromic Retinitis Pigmentosa: Associations With Causative Genes in a Large Cohort

PURPOSE. To investigate the prevalence of cystoid macular edema (CME) in relation to the disease-causing genes in a large cohort of genetically defined patients with non-syndromic retinitis pigmentosa (RP). METHODS. Spectral-domain optical coherence tomography (SD-OCT) imaging has been retrospectively reviewed in order to assess the presence of CME over the disease course in a cohort of 580 patients with a clinical and genetic diagnosis of non-syndromic RP. RESULTS. Over the course of the disease, 179 patients (30.9%) developed CME in at least one eye. Based on the patients’ genotypes, we found a statistically significant difference in CME prevalence according to the inheritance pattern (P < 0.001), with autosomal dominant forms being more frequently associated with CME (51.4%), followed by autosomal recessive forms (28.1%), but CME was rarely observed in X-linked RP (7.5%). By analyzing the most recurrent causative genes, we found the highest prevalence of CME in patients with autosomal dominant RP forms due to variants in RHO (58.2%), PRPF8 (72.7%), and PRPF3 (75.0%), whereas the lowest prevalence was observed in X-linked cases with mutations in RP2 (3.4%) and RPGR (8.8%). CONCLUSIONS. This study revealed a strong association of CME with the underlying causative gene in non-syndromic RP in the largest genotyped cohort so far reported, adding new insights in the etiopathogenesis of CME in RP. Our findings emphasize the importance of SD-OCT morphological assessments of RP patients both to improve disease management and to better explore genotype–phenotype correlations.